There is a growing need for the processing of vast amounts of data in very short periods of time. This requires higher and higher speed integrated logic circuitry. The silicon insulated gate field effect transistor, which plays an important role in these integrated circuits, will only operate up to about 4 GHz due to the low electron mobility in silicon. For this reason there is a need for the development of an insulated gate field effect transistor fabricated of a high mobility compound such as GaAs or InP.
Attempts to solve this problem in the past have not met with success, for example, Becke, et al (Solid State Electronics 8, 813 (1965)) tried silicon dioxide as a gate insulator for gallium arsenide and found it to be unsuitable due to a high interface state density between the semiconductor and the insulator which grossly degrades the device performance. Also gallium arsenide devices using silicon nitride as the gate insulator have been tried by Becke, et al, (Electronics 40, 83 (1967)). These devices operated only to about 400 MHz.